Abstract
La, Mn-codoped BaTiO3 ceramics were prepared by using high purity starting materials to clarify the influence of Mn addition on the positive temperature coefficient of resistivity (PTCR) effect. No sintering aids such as SiO2 and excess TiO2 were used. Resistivity at room temperature, grain growth and Curie temperature (TC) were studied as functions of Mn content. The Curie temperature of La-doped BaTiO3 increased initially and then decreased with increasing Mn addition, and the Mn concentration of giving the maximun TC depended on the doping concentration of La. This newly observed phenomenon is interpreted in terms of the state of Mn in the compound in connection with the variation of its bulk and grain boundary resistivity. The largest PTCR effect was observed around the concentration of Mn giving the maximum TC.
